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content__default"><h1 id="javascript高级第02天笔记"><a href="#javascript高级第02天笔记" class="header-anchor">#</a> JavaScript高级第02天笔记</h1> <p>@[toc]</p> <h2 id="_1-构造函数和原型"><a href="#_1-构造函数和原型" class="header-anchor">#</a> 1.构造函数和原型</h2> <h3 id="_1-1对象的三种创建方式-复习"><a href="#_1-1对象的三种创建方式-复习" class="header-anchor">#</a> 1.1对象的三种创建方式--复习</h3> <ol><li><p>字面量方式</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div></li> <li><p>new关键字</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div></li> <li><p>构造函数方式</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">Person</span><span class="token punctuation">(</span><span class="token parameter">name<span class="token punctuation">,</span>age</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>name <span class="token operator">=</span> name<span class="token punctuation">;</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">'zs'</span><span class="token punctuation">,</span><span class="token number">12</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div></li></ol> <h3 id="_1-2静态成员和实例成员"><a href="#_1-2静态成员和实例成员" class="header-anchor">#</a> 1.2静态成员和实例成员</h3> <h4 id="_1-2-1实例成员"><a href="#_1-2-1实例成员" class="header-anchor">#</a> 1.2.1实例成员</h4> <p>实例成员就是构造函数内部通过this添加的成员 如下列代码中uname age sing 就是实例成员,实例成员只能通过实例化的对象来访问</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token keyword">function</span> <span class="token function">Star</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function-variable function">sing</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会唱歌'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> ldh <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>ldh<span class="token punctuation">.</span>uname<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//实例成员只能通过实例化的对象来访问</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><h4 id="_1-2-2静态成员"><a href="#_1-2-2静态成员" class="header-anchor">#</a> 1.2.2静态成员</h4> <p>静态成员 在构造函数本身上添加的成员  如下列代码中 sex 就是静态成员,静态成员只能通过构造函数来访问</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token keyword">function</span> <span class="token function">Star</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function-variable function">sing</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会唱歌'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
Star<span class="token punctuation">.</span>sex <span class="token operator">=</span> <span class="token string">'男'</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> ldh <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>Star<span class="token punctuation">.</span>sex<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//静态成员只能通过构造函数来访问</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h3 id="_1-3构造函数的问题"><a href="#_1-3构造函数的问题" class="header-anchor">#</a> 1.3构造函数的问题</h3> <p>构造函数方法很好用，但是存在浪费内存的问题。</p> <p><img src="https://img-blog.csdnimg.cn/98ac2b9407514fdbb4b604a0762e8b93.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-4构造函数原型prototype"><a href="#_1-4构造函数原型prototype" class="header-anchor">#</a> 1.4构造函数原型prototype</h3> <p>构造函数通过原型分配的函数是所有对象所共享的。</p> <p>JavaScript 规定，每一个构造函数都有一个prototype 属性，指向另一个对象。注意这个prototype就是一个对象，这个对象的所有属性和方法，都会被构造函数所拥有。</p> <p>我们可以把那些不变的方法，直接定义在 prototype 对象上，这样所有对象的实例就可以共享这些方法。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">Star</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token class-name">Star</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">sing</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
	console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会唱歌'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> ldh <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> zxy <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'张学友'</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
ldh<span class="token punctuation">.</span><span class="token function">sing</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//我会唱歌</span>
zxy<span class="token punctuation">.</span><span class="token function">sing</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//我会唱歌</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><p><img src="https://img-blog.csdnimg.cn/666054f3b6784de08624c48b6a359f1c.png#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-5对象原型"><a href="#_1-5对象原型" class="header-anchor">#</a> 1.5对象原型</h3> <div class="language-html line-numbers-mode"><pre class="language-html"><code>对象都会有一个属性 __proto__ 指向构造函数的 prototype 原型对象，之所以我们对象可以使用构造函数 prototype 原型对象的属性和方法，就是因为对象有 __proto__ 原型的存在。
__proto__对象原型和原型对象 prototype 是等价的
__proto__对象原型的意义就在于为对象的查找机制提供一个方向，或者说一条路线，但是它是一个非标准属性，因此实际开发中，不可以使用这个属性，它只是内部指向原型对象 prototype
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p><img src="https://img-blog.csdnimg.cn/0ae336367c524712a44ee7a750afc84e.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-6constructor构造函数"><a href="#_1-6constructor构造函数" class="header-anchor">#</a> 1.6constructor构造函数</h3> <div class="language-html line-numbers-mode"><pre class="language-html"><code>对象原型（ __proto__）和构造函数（prototype）原型对象里面都有一个属性 constructor 属性 ，constructor 我们称为构造函数，因为它指回构造函数本身。
constructor 主要用于记录该对象引用于哪个构造函数，它可以让原型对象重新指向原来的构造函数。
一般情况下，对象的方法都在构造函数的原型对象中设置。如果有多个对象的方法，我们可以给原型对象采取对象形式赋值，但是这样就会覆盖构造函数原型对象原来的内容，这样修改后的原型对象 constructor  就不再指向当前构造函数了。此时，我们可以在修改后的原型对象中，添加一个 constructor 指向原来的构造函数。
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p>如果我们修改了原来的原型对象,给原型对象赋值的是一个对象,则必须手动的利用constructor指回原来的构造函数如:</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token keyword">function</span> <span class="token function">Star</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
     <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
 <span class="token comment">// 很多情况下,我们需要手动的利用constructor 这个属性指回 原来的构造函数</span>
 <span class="token class-name">Star</span><span class="token punctuation">.</span>prototype <span class="token operator">=</span> <span class="token punctuation">{</span>
 <span class="token comment">// 如果我们修改了原来的原型对象,给原型对象赋值的是一个对象,则必须手动的利用constructor指回原来的构造函数</span>
   <span class="token literal-property property">constructor</span><span class="token operator">:</span> Star<span class="token punctuation">,</span> <span class="token comment">// 手动设置指回原来的构造函数</span>
   <span class="token function-variable function">sing</span><span class="token operator">:</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会唱歌'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
   <span class="token punctuation">}</span><span class="token punctuation">,</span>
   <span class="token function-variable function">movie</span><span class="token operator">:</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会演电影'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
   <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> zxy <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'张学友'</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>zxy<span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div><p>以上代码运行结果,设置constructor属性如图:</p> <p><img src="https://img-blog.csdnimg.cn/88227c30c1d445bc87f99cef19d1a5d2.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-7原型链"><a href="#_1-7原型链" class="header-anchor">#</a> 1.7原型链</h3> <p>​	每一个实例对象又有一个__proto__属性，指向的构造函数的原型对象，构造函数的原型对象也是一个对象，也有__proto__属性，这样一层一层往上找就形成了原型链。</p> <p><img src="https://img-blog.csdnimg.cn/b5ad104341ae49f18cc2b69b183a9323.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-8构造函数实例和原型对象三角关系"><a href="#_1-8构造函数实例和原型对象三角关系" class="header-anchor">#</a> 1.8构造函数实例和原型对象三角关系</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token number">1.</span>构造函数的prototype属性指向了构造函数原型对象
<span class="token number">2.</span>实例对象是由构造函数创建的<span class="token punctuation">,</span>实例对象的__proto__属性指向了构造函数的原型对象
<span class="token number">3.</span>构造函数的原型对象的constructor属性指向了构造函数<span class="token punctuation">,</span>实例对象的原型的constructor属性也指向了构造函数
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h3 id="_1-9原型链和成员的查找机制"><a href="#_1-9原型链和成员的查找机制" class="header-anchor">#</a> 1.9原型链和成员的查找机制</h3> <p>任何对象都有原型对象,也就是prototype属性,任何原型对象也是一个对象,该对象就有__proto__属性,这样一层一层往上找,就形成了一条链,我们称此为原型链;</p> <div class="language-html line-numbers-mode"><pre class="language-html"><code>当访问一个对象的属性（包括方法）时，首先查找这个对象自身有没有该属性。
如果没有就查找它的原型（也就是 __proto__指向的 prototype 原型对象）。
如果还没有就查找原型对象的原型（Object的原型对象）。
依此类推一直找到 Object 为止（null）。
__proto__对象原型的意义就在于为对象成员查找机制提供一个方向，或者说一条路线。
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><h3 id="_1-10原型对象中this指向"><a href="#_1-10原型对象中this指向" class="header-anchor">#</a> 1.10原型对象中this指向</h3> <p>构造函数中的this和原型对象的this,都指向我们new出来的实例对象</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">Star</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> that<span class="token punctuation">;</span>
<span class="token class-name">Star</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">sing</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'我会唱歌'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    that <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> ldh <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Star</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 1. 在构造函数中,里面this指向的是对象实例 ldh</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>that <span class="token operator">===</span> ldh<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//true</span>
<span class="token comment">// 2.原型对象函数里面的this 指向的是 实例对象 ldh</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br></div></div><p><img src="https://img-blog.csdnimg.cn/8782b5c628d6454ea2a0b8ec93aad902.png#pic_center" alt="在这里插入图片描述"></p> <h3 id="_1-11通过原型为数组扩展内置方法"><a href="#_1-11通过原型为数组扩展内置方法" class="header-anchor">#</a> 1.11通过原型为数组扩展内置方法</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token class-name">Array</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">sum</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token keyword">var</span> sum <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
   <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">var</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> <span class="token keyword">this</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   sum <span class="token operator">+=</span> <span class="token keyword">this</span><span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
   <span class="token punctuation">}</span>
   <span class="token keyword">return</span> sum<span class="token punctuation">;</span>
 <span class="token punctuation">}</span><span class="token punctuation">;</span>
 <span class="token comment">//此时数组对象中已经存在sum()方法了  可以始终 数组.sum()进行数据的求</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><ul><li>效果图</li></ul> <p><img src="https://img-blog.csdnimg.cn/8c7514cf419a421fbcc3880d8a60d15c.png#pic_center" alt="在这里插入图片描述"></p> <h2 id="_2-继承"><a href="#_2-继承" class="header-anchor">#</a> 2.继承</h2> <h3 id="_2-1call"><a href="#_2-1call" class="header-anchor">#</a> 2.1call()</h3> <ul><li>call()可以调用函数</li> <li>call()可以修改this的指向,使用call()的时候 参数一是修改后的this指向,参数2,参数3..使用逗号隔开连接</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token keyword">function</span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token parameter">x<span class="token punctuation">,</span> y</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>x <span class="token operator">+</span> y<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
  <span class="token keyword">var</span> o <span class="token operator">=</span> <span class="token punctuation">{</span>
  	<span class="token literal-property property">name</span><span class="token operator">:</span> <span class="token string">'andy'</span>
  <span class="token punctuation">}</span><span class="token punctuation">;</span>
  <span class="token function">fn</span><span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//调用了函数此时的this指向了对象o,</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p><img src="https://img-blog.csdnimg.cn/910dd35817bc47a6a29b2f571e5f5fcb.png#pic_center" alt="在这里插入图片描述"></p> <h3 id="_2-2子构造函数继承父构造函数中的属性"><a href="#_2-2子构造函数继承父构造函数中的属性" class="header-anchor">#</a> 2.2子构造函数继承父构造函数中的属性</h3> <ol><li>先定义一个父构造函数</li> <li>再定义一个子构造函数</li> <li>子构造函数继承父构造函数的属性(使用call方法)</li></ol> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token comment">// 1. 父构造函数</span>
 <span class="token keyword">function</span> <span class="token function">Father</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token comment">// this 指向父构造函数的对象实例</span>
   <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
   <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
  <span class="token comment">// 2 .子构造函数 </span>
<span class="token keyword">function</span> <span class="token function">Son</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age<span class="token punctuation">,</span> score</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// this 指向子构造函数的对象实例</span>
  <span class="token number">3.</span>使用call方式实现子继承父的属性
  <span class="token function">Father</span><span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> uname<span class="token punctuation">,</span> age<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>score <span class="token operator">=</span> score<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> son <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Son</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">,</span> <span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>son<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><p><img src="https://img-blog.csdnimg.cn/39b9b6dce1da4ca4b39ba5380fcb988b.png#pic_center" alt="在这里插入图片描述"></p> <h3 id="_2-3借用原型对象继承方法"><a href="#_2-3借用原型对象继承方法" class="header-anchor">#</a> 2.3借用原型对象继承方法</h3> <ol><li>先定义一个父构造函数</li> <li>再定义一个子构造函数</li> <li>子构造函数继承父构造函数的属性(使用call方法)</li></ol> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token comment">// 1. 父构造函数</span>
<span class="token keyword">function</span> <span class="token function">Father</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// this 指向父构造函数的对象实例</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>uname <span class="token operator">=</span> uname<span class="token punctuation">;</span>
  <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token class-name">Father</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">money</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token number">100000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 <span class="token punctuation">}</span><span class="token punctuation">;</span>
 <span class="token comment">// 2 .子构造函数 </span>
  <span class="token keyword">function</span> <span class="token function">Son</span><span class="token punctuation">(</span><span class="token parameter">uname<span class="token punctuation">,</span> age<span class="token punctuation">,</span> score</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token comment">// this 指向子构造函数的对象实例</span>
      <span class="token function">Father</span><span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> uname<span class="token punctuation">,</span> age<span class="token punctuation">)</span><span class="token punctuation">;</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>score <span class="token operator">=</span> score<span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token comment">// Son.prototype = Father.prototype;  这样直接赋值会有问题,如果修改了子原型对象,父原型对象也会跟着一起变化</span>
  <span class="token class-name">Son</span><span class="token punctuation">.</span>prototype <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Father</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token comment">// 如果利用对象的形式修改了原型对象,别忘了利用constructor 指回原来的构造函数</span>
  <span class="token class-name">Son</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span>constructor <span class="token operator">=</span> Son<span class="token punctuation">;</span>
  <span class="token comment">// 这个是子构造函数专门的方法</span>
  <span class="token class-name">Son</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">exam</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'孩子要考试'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

  <span class="token punctuation">}</span>
  <span class="token keyword">var</span> son <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Son</span><span class="token punctuation">(</span><span class="token string">'刘德华'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">,</span> <span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>son<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br></div></div><ul><li>图解</li></ul> <p><img src="https://img-blog.csdnimg.cn/872a45745a174d70a737bb0e75732ecf.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <p>如上代码结果如图:</p> <p><img src="https://img-blog.csdnimg.cn/ba682258300e4bdbbb0d67d824ab60ba.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p> <h2 id="_3-es5新增方法"><a href="#_3-es5新增方法" class="header-anchor">#</a> 3.ES5新增方法</h2> <h3 id="_3-1数组方法foreach遍历数组"><a href="#_3-1数组方法foreach遍历数组" class="header-anchor">#</a> 3.1数组方法forEach遍历数组</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code> arr<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value<span class="token punctuation">,</span> index<span class="token punctuation">,</span> array</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
       <span class="token comment">//参数一是:数组元素</span>
       <span class="token comment">//参数二是:数组元素的索引</span>
       <span class="token comment">//参数三是:当前的数组</span>
 <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token comment">//相当于数组遍历的 for循环 没有返回值</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><h3 id="_3-2数组方法filter过滤数组"><a href="#_3-2数组方法filter过滤数组" class="header-anchor">#</a> 3.2数组方法filter过滤数组</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code>  <span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">12</span><span class="token punctuation">,</span> <span class="token number">66</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">88</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">var</span> newArr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value<span class="token punctuation">,</span> index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  	 <span class="token comment">//参数一是:数组元素</span>
     <span class="token comment">//参数二是:数组元素的索引</span>
     <span class="token comment">//参数三是:当前的数组</span>
     <span class="token keyword">return</span> value <span class="token operator">&gt;=</span> <span class="token number">20</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>newArr<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//[66,88] //返回值是一个新数组</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><h3 id="_3-3数组方法some"><a href="#_3-3数组方法some" class="header-anchor">#</a> 3.3数组方法some</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code>some 查找数组中是否有满足条件的元素 
 <span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">30</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
 <span class="token keyword">var</span> flag <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value<span class="token punctuation">,</span>index<span class="token punctuation">,</span>array</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token comment">//参数一是:数组元素</span>
     <span class="token comment">//参数二是:数组元素的索引</span>
     <span class="token comment">//参数三是:当前的数组</span>
     <span class="token keyword">return</span> value <span class="token operator">&lt;</span> <span class="token number">3</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>flag<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//false返回值是布尔值,只要查找到满足条件的一个元素就立马终止循环</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><h3 id="_3-4筛选商品案例"><a href="#_3-4筛选商品案例" class="header-anchor">#</a> 3.4筛选商品案例</h3> <ol><li><p>定义数组对象数据</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> data <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">{</span>
            <span class="token literal-property property">id</span><span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
            <span class="token literal-property property">pname</span><span class="token operator">:</span> <span class="token string">'小米'</span><span class="token punctuation">,</span>
            <span class="token literal-property property">price</span><span class="token operator">:</span> <span class="token number">3999</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token literal-property property">id</span><span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span>
            <span class="token literal-property property">pname</span><span class="token operator">:</span> <span class="token string">'oppo'</span><span class="token punctuation">,</span>
            <span class="token literal-property property">price</span><span class="token operator">:</span> <span class="token number">999</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token literal-property property">id</span><span class="token operator">:</span> <span class="token number">3</span><span class="token punctuation">,</span>
            <span class="token literal-property property">pname</span><span class="token operator">:</span> <span class="token string">'荣耀'</span><span class="token punctuation">,</span>
            <span class="token literal-property property">price</span><span class="token operator">:</span> <span class="token number">1299</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token literal-property property">id</span><span class="token operator">:</span> <span class="token number">4</span><span class="token punctuation">,</span>
            <span class="token literal-property property">pname</span><span class="token operator">:</span> <span class="token string">'华为'</span><span class="token punctuation">,</span>
            <span class="token literal-property property">price</span><span class="token operator">:</span> <span class="token number">1999</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">]</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div></li> <li><p>使用forEach遍历数据并渲染到页面中</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>data<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token keyword">var</span> tr <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">createElement</span><span class="token punctuation">(</span><span class="token string">'tr'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  tr<span class="token punctuation">.</span>innerHTML <span class="token operator">=</span> <span class="token string">'&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>id <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>pname <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>price <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;'</span><span class="token punctuation">;</span>
  tbody<span class="token punctuation">.</span><span class="token function">appendChild</span><span class="token punctuation">(</span>tr<span class="token punctuation">)</span><span class="token punctuation">;</span>
 <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div></li> <li><p>根据价格筛选数据</p> <ol><li><p>获取到搜索按钮并为其绑定点击事件</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>search_price<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div></li> <li><p>使用filter将用户输入的价格信息筛选出来</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>search_price<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">var</span> newDate <span class="token operator">=</span> data<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token comment">//start.value是开始区间</span>
        <span class="token comment">//end.value是结束的区间</span>
      	<span class="token keyword">return</span> value<span class="token punctuation">.</span>price <span class="token operator">&gt;=</span> start<span class="token punctuation">.</span>value <span class="token operator">&amp;&amp;</span> value<span class="token punctuation">.</span>price <span class="token operator">&lt;=</span> end<span class="token punctuation">.</span>value<span class="token punctuation">;</span>
      <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
      console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>newDate<span class="token punctuation">)</span><span class="token punctuation">;</span>
 <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div></li> <li><p>将筛选出来的数据重新渲染到表格中</p> <ol><li><p>将渲染数据的逻辑封装到一个函数中</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">setDate</span><span class="token punctuation">(</span><span class="token parameter">mydata</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token comment">// 先清空原来tbody 里面的数据</span>
  tbody<span class="token punctuation">.</span>innerHTML <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span>
  mydata<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">var</span> tr <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">createElement</span><span class="token punctuation">(</span><span class="token string">'tr'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    tr<span class="token punctuation">.</span>innerHTML <span class="token operator">=</span> <span class="token string">'&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>id <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>pname <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;&lt;td&gt;'</span> <span class="token operator">+</span> value<span class="token punctuation">.</span>price <span class="token operator">+</span> <span class="token string">'&lt;/td&gt;'</span><span class="token punctuation">;</span>
      tbody<span class="token punctuation">.</span><span class="token function">appendChild</span><span class="token punctuation">(</span>tr<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div></li> <li><p>将筛选之后的数据重新渲染</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> search_price<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">var</span> newDate <span class="token operator">=</span> data<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">return</span> value<span class="token punctuation">.</span>price <span class="token operator">&gt;=</span> start<span class="token punctuation">.</span>value <span class="token operator">&amp;&amp;</span> value<span class="token punctuation">.</span>price <span class="token operator">&lt;=</span> end<span class="token punctuation">.</span>value<span class="token punctuation">;</span>
     <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
     console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>newDate<span class="token punctuation">)</span><span class="token punctuation">;</span>
     <span class="token comment">// 把筛选完之后的对象渲染到页面中</span>
     <span class="token function">setDate</span><span class="token punctuation">(</span>newDate<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div></li></ol></li> <li><p>根据商品名称筛选</p> <ol><li><p>获取用户输入的商品名称</p></li> <li><p>为查询按钮绑定点击事件,将输入的商品名称与这个数据进行筛选</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> search_pro<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
     <span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
     data<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
       <span class="token keyword">if</span> <span class="token punctuation">(</span>value<span class="token punctuation">.</span>pname <span class="token operator">===</span> product<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token punctuation">{</span>
         <span class="token comment">// console.log(value);</span>
         arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>value<span class="token punctuation">)</span><span class="token punctuation">;</span>
         <span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span> <span class="token comment">// return 后面必须写true  </span>
       <span class="token punctuation">}</span>
     <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
     <span class="token comment">// 把拿到的数据渲染到页面中</span>
     <span class="token function">setDate</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div></li></ol></li></ol></li></ol> <h3 id="_3-5some和foreach区别"><a href="#_3-5some和foreach区别" class="header-anchor">#</a> 3.5some和forEach区别</h3> <ul><li>如果查询数组中唯一的元素, 用some方法更合适,在some 里面 遇到 return true 就是终止遍历 迭代效率更高</li> <li>在forEach 里面 return 不会终止迭代</li></ul> <h3 id="_3-6trim方法去除字符串两端的空格"><a href="#_3-6trim方法去除字符串两端的空格" class="header-anchor">#</a> 3.6trim方法去除字符串两端的空格</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> str <span class="token operator">=</span> <span class="token string">'   hello   '</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>str<span class="token punctuation">.</span><span class="token function">trim</span><span class="token punctuation">(</span><span class="token punctuation">)</span>）  <span class="token comment">//hello 去除两端空格</span>
<span class="token keyword">var</span> str1 <span class="token operator">=</span> <span class="token string">'   he l l o   '</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>str<span class="token punctuation">.</span><span class="token function">trim</span><span class="token punctuation">(</span><span class="token punctuation">)</span>）  <span class="token comment">//he l l o  去除两端空格</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><h3 id="_3-7获取对象的属性名"><a href="#_3-7获取对象的属性名" class="header-anchor">#</a> 3.7获取对象的属性名</h3> <p>Object.keys(对象) 获取到当前对象中的属性名 ，返回值是一个数组</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code> <span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span>
     <span class="token literal-property property">id</span><span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
     <span class="token literal-property property">pname</span><span class="token operator">:</span> <span class="token string">'小米'</span><span class="token punctuation">,</span>
     <span class="token literal-property property">price</span><span class="token operator">:</span> <span class="token number">1999</span><span class="token punctuation">,</span>
     <span class="token literal-property property">num</span><span class="token operator">:</span> <span class="token number">2000</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> result <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>result<span class="token punctuation">)</span><span class="token comment">//[id，pname,price,num]</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><h3 id="_3-8object-defineproperty"><a href="#_3-8object-defineproperty" class="header-anchor">#</a> 3.8Object.defineProperty</h3> <p>Object.defineProperty设置或修改对象中的属性</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code>Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>对象，修改或新增的属性名，<span class="token punctuation">{</span>
		<span class="token literal-property property">value</span><span class="token operator">:</span>修改或新增的属性的值<span class="token punctuation">,</span>
		<span class="token literal-property property">writable</span><span class="token operator">:</span><span class="token boolean">true</span><span class="token operator">/</span><span class="token boolean">false</span><span class="token punctuation">,</span><span class="token comment">//如果值为false 不允许修改这个属性值</span>
		<span class="token literal-property property">enumerable</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span><span class="token comment">//enumerable 如果值为false 则不允许遍历</span>
        <span class="token literal-property property">configurable</span><span class="token operator">:</span> <span class="token boolean">false</span>  <span class="token comment">//configurable 如果为false 则不允许删除这个属性 属性是否可以被删除或是否可以再次修改特性</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>	
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><h4 id="示例"><a href="#示例" class="header-anchor">#</a> 示例</h4> <div class="language-html line-numbers-mode"><pre class="language-html"><code><span class="token doctype"><span class="token punctuation">&lt;!</span><span class="token doctype-tag">DOCTYPE</span> <span class="token name">html</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>html</span> <span class="token attr-name">lang</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>en<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>head</span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>meta</span> <span class="token attr-name">charset</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>UTF-8<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>meta</span> <span class="token attr-name">http-equiv</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>X-UA-Compatible<span class="token punctuation">&quot;</span></span> <span class="token attr-name">content</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>IE=edge<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>meta</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>viewport<span class="token punctuation">&quot;</span></span> <span class="token attr-name">content</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>width=device-width, initial-scale=1.0<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>title</span><span class="token punctuation">&gt;</span></span>Document<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>title</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>head</span><span class="token punctuation">&gt;</span></span>

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>body</span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>script</span><span class="token punctuation">&gt;</span></span><span class="token script"><span class="token language-javascript">
        <span class="token comment">// 定义一个对象</span>

        <span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span>
            <span class="token literal-property property">name</span><span class="token operator">:</span> <span class="token string">'k'</span><span class="token punctuation">,</span>
            <span class="token literal-property property">age</span><span class="token operator">:</span> <span class="token number">18</span><span class="token punctuation">,</span>
            <span class="token literal-property property">sex</span><span class="token operator">:</span> <span class="token string">'男'</span>
        <span class="token punctuation">}</span>

        <span class="token comment">// 设置一个新的属性</span>

        <span class="token comment">// 三个参数，1.要修改的对象，2.要修改的对象的属性，要修改的属性的特性{对象格式}</span>
        Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>obj<span class="token punctuation">,</span> <span class="token string">'age'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token comment">// value 属性值</span>
            <span class="token literal-property property">value</span><span class="token operator">:</span> <span class="token number">100</span><span class="token punctuation">,</span>
            <span class="token comment">// writable 是否可重写属性的值 默认false</span>
            <span class="token literal-property property">writable</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
            <span class="token comment">// enumerable  属性是否可以被枚举（遍历） 默认false</span>
            <span class="token literal-property property">enumerable</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>

            <span class="token comment">// 属性是否可以被再定义 configurable 默认false</span>
            <span class="token literal-property property">configurable</span><span class="token operator">:</span> <span class="token boolean">false</span>

        <span class="token punctuation">}</span><span class="token punctuation">)</span>

        console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">;</span>

        <span class="token comment">// 1.重写</span>
        obj<span class="token punctuation">.</span>age <span class="token operator">=</span> <span class="token number">10000</span><span class="token punctuation">;</span>

        console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">;</span>

        <span class="token comment">// 2.遍历</span>

        <span class="token keyword">var</span> arr <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">keys</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">;</span>

        console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span>

        <span class="token comment">// 3.在定义</span>

        Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>obj<span class="token punctuation">,</span> <span class="token string">'age'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token comment">// value 属性值</span>
            <span class="token literal-property property">value</span><span class="token operator">:</span> <span class="token number">10000</span><span class="token punctuation">,</span>
            <span class="token comment">// writable 是否可重写属性的值 默认false</span>
            <span class="token literal-property property">writable</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
            <span class="token comment">// enumerable  属性是否可以被枚举（遍历） 默认false</span>
            <span class="token literal-property property">enumerable</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>

            <span class="token comment">// 属性是否可以被再定义 configurable 默认false</span>
            <span class="token literal-property property">configurable</span><span class="token operator">:</span> <span class="token boolean">false</span>

        <span class="token punctuation">}</span><span class="token punctuation">)</span>
    </span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>script</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>body</span><span class="token punctuation">&gt;</span></span>

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>html</span><span class="token punctuation">&gt;</span></span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br><span class="line-number">62</span><br><span class="line-number">63</span><br><span class="line-number">64</span><br><span class="line-number">65</span><br><span class="line-number">66</span><br><span class="line-number">67</span><br></div></div><ul><li>效果图</li></ul> <p><img src="https://img-blog.csdnimg.cn/083ddfc9519a49b2a2a0c1caec958395.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5YeM5q2G,size_20,color_FFFFFF,t_70,g_se,x_16#pic_center" alt="在这里插入图片描述"></p></div></div>  <div class="page-edit"><div class="edit-link"><a href="https://github.com/linxin1123/vuepress-blog/edit/master/docs/01.前端/43.JavaScript高阶笔记/02.js高级day02.md" target="_blank" rel="noopener noreferrer">编辑</a> <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></div> <!----> <div class="last-updated"><span class="prefix">上次更新:</span> <span class="time">2023/02/17, 11:29:32</span></div></div> <div class="page-nav-wapper"><div class="page-nav-centre-wrap"><a href="/pages/b37244/" class="page-nav-centre page-nav-centre-prev"><div class="tooltip">js高级day01</div></a> <a href="/pages/f50f4e/" class="page-nav-centre page-nav-centre-next"><div class="tooltip">js高级3</div></a></div> <div class="page-nav"><p class="inner"><span class="prev">
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